Process for recovering borax from brine



' April 29, 1930.

H. D. HELLMERS l PROCESS FOR RECOVERING BORAX FOM BRINE Filed Oct. 24, 1925 2 Sheets-Sheet l gwumatoz bw ow ov .uw QN 9 u flor neg April 29, 1930.4 H. D. HELLMERS PROCESS FOR RECOVERING BORAX FROM BRINE 2, Sheets-Sheet 2 Filed OCC. 24, 1925 Ng. k.,

Patented Apr. 29, 1930 U EDl STATES PATENT Feier;

HENRY D. HELLMERS, OF WESTEND, CALIFORNIA, ASSIGNOR TO WEST END CHEMICAL COMPANY, OF OAKLAND, CALIFORNIA, A CORPORATION OF CALIFORNIA PROCESS FOR RECOVERING BORAX FROM BRINE l vApplication filed October 24, 1925. Serial No. 64,686.

This invention relates to methods of recovering or separatin g borax from natural brines containing boratesof sodium together with other salts particularly carbonates of Asodium in solution.

- Among such brines may be mentioned the brine of Searles Lake, California. Following is a typical analysis of brine from4 this lake:

a G. p. 1. NaCl 210 NagSOa Naf/O3 62.1

KCl 66.7

B203 as sodium borates 14.5

This brine contains about three times as much carbonates of sodium as it does borates of sodium'and'the particular object of this in- `vention is to effect through simple operations the recovery and sepa-ration from each other of a large part of the boraX and soda content. In the treatment of such brine with carbonicacid gas for the precipitation of the carbonates largely as bicarbonates, I have discovered a change in the borax suspending properties of the liquid, that will permit the recovery and separation of a large part of the soda content and obtain a solution, from which the maximum amount of boraX may be crystallized. p The chart #l accompanyingr this application shows graphically the average concentration of bora-X and sodium carbonates in brine as it is'pumped in its raw state from Searles Lake and the change in concentration of these substances during treatment with carbonio acid gas, carried out at temperatures below degrees centigrade.,

In the chart, the initial concentration in grams per liter of both salts is taken at the right hand end of the chart, the figures along the base line indicating the changing concentration of the sodium carbonates and the curve indicating the relative changing concentration of the boraX as taken against the values of the vertical scale. When the brine is treated with carbonio-acid gas. by any suitable means, a precipitation of the carbonates of sodium, either as double salts or as bi-car- 5o bonate results, as well as a precipitation of some of the boraX, probably in the form of tetraborate to be later redissolved as treatment progresses. Upon continuing the gas treatment, the carbonate concentration falls Jfrom the initial 60 or more grams per liter and if lowered to about ten g. p. l. or less, then the largest part of the bor-ax that may have crystallized during the progress of the CO2 treatment, will have gone back into solution,

vthus leaving but very little-borax precipitated even if cooled or agitated.

I'believe the following to be the explanation of the behavior of the borax and soda during carbonation as ldescribed above:

First the CO2 gas reacts with sodium carbonate to form bicarbonate NagC O3 plus C02 plus H2Ov QNaHCO;

and with the sodium metaborate present to form sodium tetraborate 2Na2B2O4 plus 2G02 plus H2O NazBiOT plus 2NaIICO3 This results in an increased solubility of ltotal B203 and the borax that is precipitated durl ing earlier stages of carbonation at lower temperatures goes back into solution, as soon as enough excess of CO2 has been applied.

When the carbonation is carried out at temperatures above 25 degrees no'borax will be crystallized at any stage of the carbonation due to' the increased solubility of tetraborate at' these higher temperatures. See chart #2.

Should this be the case, then at the end of the CO2 treatment a liquor is obtained, that is vessentially the same as if the temperature had been lower. In cha-rt #2 the curve is essentially -straight as shownv b v line B. If

lished Where all of the borax is converted to the tetraborate.

21331303 plus NagBz04 N842B407 plus BH2Cv m5213104 plus zoozpius 2R10 NaiB401 plus zNanoo, This results ina solution supersaturated with respect to tetraborate and this may be crystallized out by cooling tol less than 25 degrees,

if necessary, and preferably applying agita'- tion also. The reduction of the 'carbonate concentration to about 7 to 8 g. p. l. or less is not necessarily the critical point, but is found to be a satisfactory concentration for carrying out 'the process described. f

The process may be varied by carbonating vthe brine above 23 degreescentigrade until part of the carbonate content of the brine has which consists in treating th'e brine With' CO2 Auntil any boraX that hasv been precipitated during the earlier stages of the carbonization has been largely redissolved, separating the-precipitatedl salts of sodium from the solution and crystallizing out the boraX.

' HENRY 'D-HELLMERSQ v L been precipitated. Itwill be foundthat. at

e temperatures above 23 degrees centrigrade practically no boraX Will crystallize duringthe carbbnation. If the carbonation is then stopped, Aiir'hen the carbonate content is down to about 14 g. p. l; and the brine then cooled. Vand preferably agitated, vnearly pure borax will crystallize. I dofnot regard 14 g. p. l. as

being the critical point, but prefer 'to stop carbonating about there. It is understood present.

In either `casethe precipitated or crystal-7 lized boraX may be separated from the mother liquor by any suitable means and then further purified by `Washing or recrystallizing as desired.

In contemplating-my invention as above set forth, it should be noted .that dit involves on commercial scale the precipitation of nearly pure boraX from raw lake brine that has not undergone any preliminary concentrating vtreatment by evaporation as Well asfrom 'brine that has undergone suoli treatment.y It is the discovery of the changing/of the solubility of boraX in the brine during the different stages of treatment With CO2 gas, as indicatedby the chart, upon Which my inven' tion is based. `It also involves the separation t of borax from sodaand recovery of both i in commercial quantities from"raw brine.l

" I claim:

[treating the b 'preoipitate so l. The method of vrecovering boraX from :brine containing borate in solution together AWit-h ,sodium carbonate, which consists 1n vvith carbonio 'acid gas to ,l l e carbonates, removing 'the precipitatedc bonates from the solution,

and crystallizing ont the-bor'ax by'cooling. -j

2. rIhe process oiffj'treatingbrine containing that during the gas treatment of the bri-nel an-excess of CO2 gas may.ormay not be l carbonates of sodiiiin and. sodium borates,

iso 

